Heat-shrinking furnace for the formation of bundles with improved film adhesion

ABSTRACT

A heat-shrinking furnace for forming bundles of products wrapped in a heat-shrinkable film and defining at least one channel for advancement of the bundles along an advancement direction, and including: an inlet fed by the bundle of products in succession one after the other, the products being tunnel-wrapped in a loose manner by the heat-shrinkable film to identify two lateral openings orthogonal to the advancement direction; an outlet for release of the bundles of products wrapped in a compact manner by the heat-shrinked film; a heater operating between the inlet and outlet for making heat-shrinking of the film on the products; and wherein in an intermediate position between the inlet and the outlet the furnace includes a mechanism for temporarily holding the heat-shrinkable film spaced apart from the products at the lateral openings during heat shrinking.

The present invention concerns a heat-shrinking furnace for forming bundles of products that are wrapped by films made in a heat-shrinkable material.

A further object of the present invention is a process for heat-shrinking films made in a heat-shrinkable material that is intended to form bundles of containers.

The object of the present invention is particularly used in the field of packaging products such as bottles, cans and/or similar containers in which wrapping films to be used are provided and realized in a heat-shrinkable material that is intended to form respective bundles.

As it is known, the formation of bundles of containers by heat-shrinking is generally carried out with the aid of suitable furnaces defining at least one advancement channel for the bundles.

Tunnel furnaces are provided with an inlet opening for continuously introducing separate groups of containers wrapped by respective heat-shrinkable films and with an outlet opening for the continuous outlet of respective bundles of heat-shrunk containers.

During heat-shrinking the plastic film shrinks becoming compact against the products and therefore making the finished bundle compact.

However, the Applicant has found that during the step of heat-shrinking the film, the latter stops or slows down abruptly, in the moment in which it comes into contact with the wall of the products.

The reason why such a phenomenon occurs is that usually the products have a lower temperature and during the shrinking step the hot film, coming into contact with the container, undergoes cooling such as to stop or slow down the shrinking.

Such a phenomenon can be seen more clearly in the open side areas of the bundle in which the overlapping portions of the film could shrink much more than what usually actually occurs.

Starting from the aforementioned current state of the art, the main purpose of the present invention is to propose a furnace and a process for heat-shrinking bundles in which the film, for the same materials and sizes, can shrink more and thus make the finished bundle more stable.

A further purpose of the present invention is to reduce the overall consumption of energy necessary in order for the furnaces to operate in an optimal manner.

The purposes specified above, and yet others, are substantially achieved with a furnace and with a process for heat-shrinking films made in a heat-shrinkable material that is intended for realizing bundles of containers, in accordance with the present invention.

The description shall be made in the rest of the document with reference to the attached drawings, which are provided purely as an indication and therefore not for limiting purposes, in which two examples of a furnace according to the present invention are shown.

FIG. 1 shows a top view of the furnace according to the present invention;

FIG. 2 shows a side view of the furnace of FIG. 1.

Such a heat-shrinking furnace 10 is suitable for forming bundles 11 of products 12 that are wrapped by a heat-shrinkable film 13.

The furnace is of the type defining at least an advancement channel 14 for the bundles 11 along the advancement direction X and comprises:

-   -   an inlet 15 which is fed by a bundle 11 of products in         succession one after the other, said products being         tunnel-wrapped in a loose manner by heat-shrinkable film 13 so         as to identify two lateral openings 17 that are orthogonal to         the advancement direction X;     -   an outlet 16 for the release of the bundles 11 of products 12         wrapped in a compact manner by the heat-shrinkable film 13;     -   heating means operating between the inlet 15 and the outlet 16         for making the heat-shrinking of the film 13 on the products 12.

According to the invention, in an intermediate position between the inlet 15 and the outlet 16, the furnace comprises means to temporarily hold the heat-shrinkable film 13 spaced apart from the products 12 at the lateral openings 17 during heat-shrinking.

According to a preferred embodiment the means to temporarily hold the heat-shrinkable film 13 spaced apart from the products 12 at the lateral openings 17 during the heat-shrinking step comprise means for generating an air blow 19.

Such a blow 19 is at least partially directed along the advancement direction X in an intermediate position between the inlet 15 and the outlet 16 at both lateral walls 18 of each advancement channel 14, so that the blows 19 penetrate inside the lateral openings 17 of the heat-shrinkable film 13 that is wrapped in a loose manner on the containers 12.

In such a way the heat-shrinkable film 13 is held temporarily spaced apart from the products 12 at the lateral openings 17.

In one first version the means for generating an air blow 19 at least partially directed along the advancement direction X comprise, for each wall 18 of the channel 14, a blowing device 20 directed inclined towards the channel 14 so as to directly intercept the openings 18.

In a second version the means for generating an air blow 19 at least partially directed along the advancement direction X comprise, for each wall 18 of the channel 14, a blowing device 20 that is directed towards a deflecting element 21 arranged on the respective wall 18.

Such a deflector 21 is configured so as to reflect the blow 19 towards the openings 18.

Finally, a third version is provided in which the deflectors act directly on the air per se fed to the furnace from the walls of the channels 18.

The method implemented by the furnace 10 described above comprises the steps of:

-   -   feeding into a heat-shrinking furnace a bundle 11 of products 12         in succession one after the other, said products being         tunnel-wrapped in a loose manner by the heat-shrinkable film 13         so as to identify two lateral openings 17 that are orthogonal to         the advancement direction X;     -   heating the film 13 during the advancement of the bundle 11 into         the furnace 10 for making the heat-shrinking of the film 13 on         the products 12;     -   releasing the bundles 11 of products 12 wrapped in a compact         manner by the heat-shrinkable film 13.

In particular, the method also comprises the step of:

-   -   holding the heat-shrinkable film 13 temporarily spaced apart         from the products 12 at the lateral openings 17 during         heat-shrinking.

Such a last step is made by dispensing air blows directed in a manner such as to “enter” the lateral openings of the bundle thus holding the film spaced apart from the products at least in the first steps of the heat-shrinking.

Such air blows can be directly oriented inclined towards the openings or they can be reflected in such a direction by suitable deflectors.

The object of the present invention solves the drawbacks found in the prior art and achieves important advantages in which, in particular the film, for the same materials and sizes, can be shrunk to a greater extent and thus make the finished bundle more stable. 

1.-10. (canceled)
 11. A heat-shrinking furnace for forming bundles of products wrapped in a heat-shrinkable film, the furnace defining at least one channel for advancement of the bundles along an advancement direction, and comprising: an inlet fed by the bundles of products in succession one after the other, the products being tunnel-wrapped in a loose manner by the heat-shrinkable film to identify two lateral openings orthogonal to the advancement direction; an outlet for release of the bundles of products wrapped in a compact manner by the heat-shrinkable film; heating means operating between the inlet and the outlet for making the heat-shrinking of the film on the products; and in an intermediate position between the inlet and the outlet, means for temporarily holding the heat-shrinkable film spaced apart from the products at the lateral openings during heat-shrinking, the means for temporarily holding the heat-shrinkable film spaced apart from the products at the lateral openings during heat-shrinking comprising means for generating an air blow that is at least partially directed along the advancement direction, the means being arranged in an intermediate position between the inlet and the outlet at both lateral walls of each advancement channel, so that the blows, by penetrating into the lateral openings of the heat-shrinkable film wrapped in a loose manner on the containers, hold the heat-shrinkable film temporarily spaced apart from the products at the lateral openings; wherein the means for generating an air blow, which is at least partially directed along the advancement direction, comprises, for each wall of the channel, a blowing device directed towards a deflecting element arranged on the respective wall, the deflector being configured for reflecting the blow towards the openings.
 12. A furnace according to claim 11, wherein the walls are fed by air along substantially their entire development and include holes for supply of the air into the channel substantially in a direction orthogonal to the advancement direction, the means for temporarily holding the heat-shrinkable film spaced apart from the products at the lateral openings during heat-shrinking comprises deflectors arranged in an intermediate position between the inlet and the outlet at both lateral walls of each channel to direct, where present, air exiting from the walls at least partially along the advancement direction so that the air, by penetrating into the lateral walls of the heat-shrinkable film wrapped in a loose manner on the containers, holds the heat-shrinkable film temporarily spaced apart from the products at the lateral openings.
 13. A method for heat-shrinking for forming bundles of products wrapped by a heat-shrinkable film, the method comprising: feeding into a heat-shrinking furnace in succession one after the other a bundle of products, which is tunnel-wrapped in a loose manner by the heat-shrinkable film to identify two lateral openings orthogonal to the advancement direction; heating the film during advancement of the bundle into the furnace for making the heat-shrinking of the film on the products; releasing the bundles of products wrapped in a compact manner by the heat-shrinked film; holding the heat-shrinkable film temporarily spaced apart from the products at the lateral openings during heat-shrinking; wherein the holding the heat-shrinkable film temporarily spaced apart from the products at the lateral openings during heat-shrinking includes generating an air blow at least partially directed along the advancement direction so that the blows penetrate into the lateral walls of the heat-shrinkable film wrapped in a loose manner on the containers; and wherein the generating an air blow which is at least partially directed along the advancement direction so that the blows penetrate into the lateral walls of the heat-shrinkable film wrapped in a loose manner on the containers includes supplying an air blow directed towards a deflector element arranged on the respective wall, the deflector being configured to reflect the blow towards the openings.
 14. A method according to claim 13, wherein the holding the heat-shrinkable film temporarily spaced apart from the products at the lateral openings during heat-shrinking is made through reflection of an air flow exiting from the walls. 